BOSTON - Police locked down the Boston area and searched house-to-house for a suspect in the marathon bombing after a second suspect, his older brother, was killed in an overnight gun battle.

Dzhokar Tsarnaev, a 19-year-old immigrant who has been in the U.S. for several years, escaped during a confrontation with police in the Boston suburb of Watertown in which at least one person hurled explosive devices at police, according to a federal law enforcement official.

Tsarnaev was born in Kyrgyzstan, and his older brother Tamerlan, the second suspect who was killed, was born in Russia, according to two U.S. law enforcement officials who asked for anonymity because they weren’t authorized to discuss the matter. At least one of the two was a naturalized U.S. citizen, according to the officials.

Massachusetts Governor Deval Patrick asked all residents of Boston and several surrounding suburbs to “shelter in place” and stay inside with their doors locked and allow in only police. Public transit was shut down for the area.

“There is a massive manhunt underway,” Patrick said in a news conference.

Tsarnaev ran over his brother Tamerlan during the shoot-out in Watertown, according to the official. The brother was first identified as 20 and officials later corrected that to 26. One law enforcement officer also was killed and another was seriously wounded in mayhem that began at 10:30 pm local time last night.

Investigators believe the dead brother had explosives strapped to his body when he was killed, according to two federal law enforcement officials. That increased concerns about the type of weaponry the younger Tsarnaev had on him, one of the officials said.

Maryland relatives

Authorities were searching the brothers’ residence in Cambridge, Mass., this morning. The FBI was conducting interviews with relatives of the two this morning at a home in the Washington suburb of Gaithersburg, Maryland, according to Richard Wolf, an FBI spokesman.

A profile attributed to Dzhokar on the Russian social networking site V kontakte lists “career and money” as his personal priority and Islam as his world view.

A video posted April 9 on his page called “For those who have a heart” is about the Syrian civil war.

“They’re killing your brothers and sisters without any reason, just because they say ‘our god is Allah’ and ‘Mohammed is our prophet,” it says, asking people to help the Syrians.

Brothers immigrated

The Tsarnaev brothers and their two sisters moved to the Dagestan region of Russia in October 2001 from the central Asian nation of Kyrgyzstan as refugees, and left for the U.S in March 2002, said Emirmagomed Davudov, director of Gimnasium Number 1 in Dagestan, where Tamerlan went to the 7th grade and Dzhokhar to first grade.

Ruslan Tsarni, their uncle in Gaithersburg, said his brother’s children immigrated to the U.S. in 2003, arriving in Cambridge. Asked for a possible motive for the attacks, Tsarni called them “losers not being able to settle themselves and thereby just hating everybody who did.”

Images released by the FBI yesterday showed one suspect wearing a black hat, the other a white hat. Police were searching for the man identified as the “white hat” suspect, Massachusetts State Police Colonel Timothy Alben told reporters.

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